Corrosion resistant vinyl coated metal articles

ABSTRACT

VINYL COATED METAL ARTICLES ARE RENDERED CORROSION RESISTANT BY APPLYING THEREON AN ALKALI METAL DIALKYL PHOSPHOSPHATE OF THE FORMULA:   (R-O)2-P(=O)-O-M   WHEREIN R IS AN ALKYL GROUP CONTAINING FROM ABOUT 8 T ABOUT 16 CARBON ATOMS INCLUSIVE, AND M IS AN ALKALI METAL ION.

"United States Patent Oflice 3,734,783 Patented May 22, 1973 3,734,783CORROSION RESISTANT VINYL COATED METAL ARTICLES Harold McDonald,Harrington, N.J., assignor to Staulfer Chemical Company, New York, N.Y.

No Drawing. Original application July 24, 1968, Ser. No. 747,095, nowabandoned. Divided and this application May 10, 1971, Ser. No. 142,011

Int. Cl. C23f 7/10 US. Cl. 148-615 R 6 Claims ABSTRACT OF THE DISCLOSUREVinyl coated metal articles are rendered corrosion resistant by applyingthereon an alkali metal dialkyl phosphate of the formula:

II RO-P-OR wherein R is an alkyl group containing from about 8 to about16 carbon atoms inclusive, and M is an alkali metal ion.

RELATED APPLICATION This application is a division of application Ser.No. 747,095, filed July 24, 1968 now abandoned.

This invention relates to vinyl coated metal articles having depositedthereon an alkali metal dialkyl phosphate. More particularly, it relatesto vinyl coated exterior automotive roof coverings which are renderedcorrosion resistant when applied to the metal roof by having coatedthereon a minor but effective amount sufficient to inhibit corrosion ofan alkali metal dialkyl phosphate of the formula:

wherein R is an alkyl group containing from about 8 to about 16 carbonatoms inclusive, and M is an alkali metal As is well known, polyvinylchloride resin is subject to deterioration by both heat and ultravioletlight. While a number of stabilizers have been employed to inhibit thesedeleterious effects, the recent practice of coating metal articles withpolyvinyl chloride coated fabric requires the provision of stabilizerswhich inhibit corrosion on the metal surface as well as inhibitdecomposition of the vinyl chloride resin. These problems areparticularly troublesome for automobiles having vinyl hard tops as theseautomobiles are often subject to severe weather conditions. Accordingly,within a short time after application, rust develops between the metalsubstrate and the polyvinyl chloride coated fabric. Although the vinylcar top application is a relatively new application, it has become verypopular and presently represents a substantial proportion of totalproduction. Accordingly, it has become highly desirous that a solutionto this corrosion problem be provided.

In accordance with this invention, it has been discovered that theaforesaid problems can be obviated or substantially reduced byincorporating with the vinyl chloride metal article, a minor buteffective amount sufiicient to inhibit corrosion of an alkali metaldialkyl phosphate of the formula:

wherein R is an alkyl group containing from about 8 to about 16 carbonatoms inclusive, and M is an alkali metal ion.

Illustrative of the alkali metal ions are sodium lithium and potassium.While ammonium is not truly a member of the alkali metal series, it is aclear equivalent for the alkali metal ions and is generally consideredto be within the term of an equivalent of alkali metals. It is soconsidered in the present case. Sodium ions and ammonium ions arepreferred in the present invention because of their low cost andefficiency. Illustrative of the alkyl groups as represented by thesubstituent R are octyl, nonyl, decyl, undecyl, dodecyl, tridecyl,tetradecyl, pentadecyl, hexadecyl and the like, or mixtures thereof. Ofthese substituents represented by R, decyl has been found to bepreferred as such compounds provide exceptional corrosion inhibitingproperties. Particularly preferred for similar reasons are the brancheddecyl groups wherein the decyl group is derived from a highly branchedprimary alcohol.

In accordance with this invention, the alkali metal dialkyl phosphatecan be applied to the metal surface, to the polyvinyl chloride resin, orpreferably to a fabric which is to be coated with polyvinyl chlorideresin. Although the alkali metal dialkyl phosphate inhibitor can beapplied in concentrated form, it is preferred that it be dissolved in asuitable solvent. Exemplary of suitable solvents are the petroleumhydrocarbons, such as naphtha; the aromatic hydrocarbons such as,benzene; the chlorinated hydrocarbons such as, perchlorethylene; and thealcohols such as, methanol, ethanol, or hexylene glycol. If desired, thephosphate inhibitor can also be employed with water in which it issparingly soluble but forms a stable emulsion. The amount of alkalimetal dialkyl phosphate inhibitor can vary from about 25 ppm. to about100% based on the concentration of aqueous or hydrocarbon solvent.Generally, however, an inhibitor concentration of from about 0.05% toabout 20% is preferred for reasons for economy.

While the inhibitor can be employed to advantage with any metalsubstrate, the inhibitors are particularly effective with ferrousmetals.

The vinyl chloride resins useful in the practice of this invention arepolyvinyl chloride resin and copolymers of at least of vinyl chlorideand up to 30% of other polymerizable mono-olefinic monomers compatiblewith vinyl chloride. Examples of compatible monomers include: vinylcarboxylate esters, e.g., vinyl acetate, and other vinyl esters of monocarboxylic acids particularly those having from one to five carbonatoms; maleic and fumaric acids as well as the alkyl esters such asethylmaleate and ethylfumarate; alkyl esters of acrylic acids,particularly those wherein the alkyl radical has from one to four carbonatoms such as ethyl and methyl acrylate; as well as acrylic andmethacrylic acids; maleic anhydride; itaconic and aconitic acids andvinylidene chloride. These polymers and copolymers can be prepared byany of the well-known methods such as, polymerization in aqueousemulsion.

The vinyl resin can be employed with or without stabilizer butpreferably the stabilized vinyl resin is employed. Exemplary of suitablestabilizers are the organic phosphites, metallic soaps such as calciumor zinc stearate, fatty acids such as stearic acid, phenolic compoundsincluding substituted phenols, barium or cadmium phenolates,phosphinates, phosphonates, mercaptides and sulfides, epoxidized fattyoils, episulfides and epoxides, indoles, lead soaps, including leadnaphthenates, polyols, such as sorbitol or pentaerythritol, esters ofaminocrotonic acid, dialkyltin carboxylates or mercaptides,alkylstannoic acids, urea or thiourea derivatives, as well as otheradditives, known in the art of polyvinyl polymer stabilization toinclude fillers such as carbon black and titanium dioxide, etc.

For use as car tops, one suitable method of application is as follows:The vinyl resin is applied to a fabric such as cotton sateen, cottondrill, rayon sateen, polyester/ cotton blended fibers drill, etc., andbleached and finished with a fluorinated hydrocarbon type waterrepellent, such as Du Pont Zepel D. The fabric is then calender coatedwith a solid-plasticized and pigmented polyvinyl chloride resincomposition. A topcoat consisting of a solvent solution (methyl-ethylketone solvent) of polyvinyl chloride and polymethyl mcthacrylate resinsis roller knife coated onto the calendered vinyl. The construction isthen embossed in the desired grain, trimmed and applied with adhesive tothe hard top.

The following examples will serve to illustrate the invention and itspreferred embodiments. All parts and percentages are by weight unlessotherwise specified.

Example 1 In accordance with the conventional procedure, samples ofcotton sateen, cotton drill, cotton osnaburg, rayon sateen, rayon drilland polyester cotton drill were sprayed on one side with a polyvinylchloride emulsion grade resin (Geon 121). The resin was stabilized witha mixture of barium-cadmium phenolates, organic phosphites, andcalcium-zinc stearate; and plasticized with dioctyl phthalate. The resinwhich contained 50 parts plasticizer, 30 parts calcium carbonate filler,and 5-6 parts stabilizer per 100 parts resin was applied in aconcentration of approximately 16 ozs. per square yard of fabric. Thefabrics were sprayed with from between 1.11 grams and 1.56 grams (dryweight) of adhesive and allowed to dry for minutes at room temperature.The fabrics measuring 8 inches by 8 inches were then applied to adhesivecoated unpainted steel 10 inch by 10 inch panels, having sprayed thereonbetween 1.73 to 2.43 grams (dry weight) of the same adhesive, secondsafter application. The assemblies were allowed to air dry forapproximately 16 hours at room temperature and then placed in a woodenrack in the vertical position. The racks were placed into an aircirculating oven for 10 minutes at a temperature of approximately 240 F.until the surface temperature of the vinyl cover was between 180 F. and185 F. The samples were then taken from the oven and immediatelyimmersed in water for 2 minutes, the water temperature not exceeding 75F. The samples were allowed to dry for 48 hours at room temperature andthen the immersion and drying steps were repeated. The samples were theninspected for rust by visual inspection, and rust was observed.

The test was then repeated but for the exception that fabrics weresprayed on one side with 55% solution of sodium didecyl phosphatedissolved in naphtha until the surface was visibly wet. The fabrics werethen allowed to air dry and coated with the vinyl resin on the side nottreated with the phosphate and then tested in accordance with theaforesaid procedure. Upon visual examination, no rust was noted on thetreated sample.

Example 2 In accordance with the previous example, a 5% solution ofsodium didecyl phosphate dissolved in naphtha was employed and no rustformation was noted.

Example 3 In accordance with the previous examples, sodium dioctylphosphate is employed as the stabilizer and the results are in generalagreement with Examples 1, and 2.

Example 4 In accordance with the previous examples, the tests arerepeated but for the exception that the phosphate inhibitor is appliedto the metal substrate. No rust formation is noted on the phosphatetreated articles.

Although the phosphate inhibitor can be applied to the metal, to thevinyl resin or to a fabric which is later coated with the vinyl resin,the latter method is preferred when the vinyl resin is to be applied toan automobile roof. While the exact mechanism of the invention is notknown, it is known that moisture gets between the fabric and the metaland that nearly all of the materials employed tend to corrode or promotecorrosion. Exemplary of these latter materials, are the water repellentssuch as the fiuorinated hydrocarbons and even the commonly employedadhesives contain chemicals which promote corrosion.

What is claimed:

1. A corrosion resistant article consisting essentially of a ferrousmetal substrate, a vinyl chloride resin bonded with adhesive to asurface thereof, said vinyl chloride resin containing a minor buteffective amount of a corrosion inhibitor sufficient to inhibitcorrosion of the metal substrate at the bond interface, said corrosioninhibitor being an alkali metal dialkyl phosphate of the formula:

wherein R is an alkyl group containing from 8 to 16 carbon atoms,inclusive, and M is an alkali metal ion.

2. A corrosion resistant article of claim 1 wherein the phosphate issodium didecyl phosphate.

3. A corrosion resistant article of claim 1 wherein the phosphate issodium dioctyl phosphate.

4. A corrosion resistant metal article consisting essentially of aferrous metal substrate having bonded thereto with adhesive a waterrepellent fabric having coated thereon at the bond interface a minor buteffective amount of a corrosion inhibitor suflicient to inhibitcorrosion of said metal substrate at said bond interface, said corrosioninhibitor being an alkali metal dialkyl phosphate of the formula:

wherein R is an alkyl group containing from -8 to 16 carbon atoms,inclusive, and M is an alkali metal ion, said fabric having coatedthereon on the side opposite the bond interface a vinyl chloride resin.

5. A corrosion resistant article of claim 4 wherein the phosphate issodium didecyl phosphate.

6. A corrosion resistant article of claim 4 wherein the phosphate issodium dioctyl phosphate.

References Cited UNITED STATES PATENTS 2,224,695 12/1940 Prutton 252-4983,277,042 10/1966 Richart l486.15 R 2,791,495 5/1957 Rudel 252-3893,087,848 4/1963 Rash 156-280 3,197,496 7/1965 LeSuer 252-81 2,997,4548/1961 Leistner 260-457 3,397,150 8/1968 Burt 252-389 2,337,424 12/1943Stoner et al. 260-457 2,873,196 2/1959 Baevsky 148-615 R 2,886,5465/1959 Dibert et al. 260-296 2,952,699 9/1960 Norman 260-461 OTHERREFERENCES Chem. Abstracts, vol. 54, 8152f, 1960.

RALPH S. KENDALL, Primary Examiner US. Cl. X.R.

